For implanted devices which acquire power from an external source, a key aspect for satisfactory performance is the efficiency of power transmission to the implanted device. In devices such as cochlear implants, the technique of using an inductive link to transfer power and/or data to the implanted device has been used. Conventional metal packages reduce the efficiency of inductive transfer. One way to address this problem is by utilising a ceramic package containing the receiving coil, instead of the conventional metal package. This arrangement provides reduced attenuation of the RF Field. However, such a package must be effectively sealed, without damaging the components within the package.
One prior art technique is disclosed in U.S. Pat. No. 4,991,582 to Byers et al. Here, the open end of the ceramic package is closed using a metal band bonded to the open end of the package using a metallic braze, and the band is ultimately sealed to a header by spot welding. A similar arrangement is disclosed in U.S. Pat. No. 4,785,827 to Fischer.
in these arrangements, the biocompatability of the resulting package may be compromised by the materials used, particularly the braze. There is also a the risk of degradation or corrosion along, or as a result of, the braze.